Conventionally, as a warmer device for a vehicle seat, a temperature control system has generally been used so as to maintain a warming member formed of a cord-like heater and the like at a constant temperature by a thermostat. However, in this kind of temperature control system operated by a thermostat, the temperature of the warming member is determined by an operating temperature of the thermostat which is being used. Therefore, in order to satisfy a demand for freely setting the temperature of the warmer device for the vehicle seat and improving the comfortability, the number of parts has to be increased or a complicated circuit configuration has to be used by employing a method using a plurality of thermostats with different operating temperatures, or a method switching a heating value of an auxiliary heater which operates the thermostat, so that the realization was difficult in practice.
In order to satisfy the above-mentioned demands, for example, the warmer device for the vehicle seat as shown in FIGS. 7, 8 are known. In FIGS. 7, 8, a temperature control circuit 101 is connected in series to a warming member 104 wherein a cord-like heater 103 is meanderingly provided in a base material 102. The temperature control circuit 101 is connected to the warming member 104 outside the base material 102, and near the cord-like heater 103, a temperature detecting element 105 such as a thermistor and the like is arranged. By controlling a current control device such as a power MOS FET and the like embedded in the temperature control circuit 101 by a temperature signal from the temperature detecting element 105, the temperature of the warming member 104 is controlled. This kind of structure is disclosed in, for example, the conventional technology of Japanese Patent Publication 1.
Also, as a publication wherein the technology which conducts the temperature control using the temperature detecting element such as the thermistor and the like is disclosed, many publications are known in addition to the above-mentioned Japanese Patent Publication 1. For example, Japanese Patent Publication 2 and the like are disclosed.    Japanese Patent Publication 1: Unexamined Patent Application Publication No. 2003-217796    Japanese Patent Publication 2: Japanese Patent Publication (Tokuhyo) No. 2004-504082